Members of the Wnt gene family are key regulators of pattern formation in a wide variety of metazoan species, and of oncogenic processes in mammals. The work proposed here is directed at understanding the role of Wnt genes expressed at the onset of kidney morphogenesis in the mouse. It exploits three aspects of the mouse developmental system: 1) the possibility to generate transgenic animals, 2) the amenability of kidney rudiments to explant culture, and 3) the extensive knowledge of transcription and growth factors associated with various aspects of kidney formation. These tools will be used to analyze the functions of Wnt-6, Wnt-7B and Wnt-11 in kidney organogenesis. In view of the apparent conservation of Wnts in various phylogenetic groups, the information obtained from the proposed research is likely to have broad applications towards understanding the function of Wnt gene subfamilies in disease and oncogenic states in humans and will tap an as yet relatively unexplored role of Wnts in the regulation of organ development in vertebrates.